Rotating device

Abstract

A rotating device includes a fixed body having a base and a shaft, a hub, and a rotating body having a rotating-body-side encircling member fixed to the hub and encircling the shaft. A lubricant is present between the fixed body and the rotating body. The rotating-body-side encircling member and the shaft are each formed with a radial dynamic pressure generating groove. The fixed body includes a base-side encircling member having a disk part encircling the base-side portion of the shaft and a cylinder part encircling the rotating-body-side encircling member. The base-side encircling member has the disk part fixed to the shaft by interference fitting, and has the cylinder part fixed to the base. An air-liquid interface is located in a gap in the radial direction between the inner periphery of the cylinder part and the outer periphery of the rotating-body-side encircling member.

What is claimed is: 
     
         1 . A rotating device comprising:
 a fixed body including a base formed with a through-hole, a base-side encircling member fixed to the through-hole, and a shaft fixed to the base-side encircling member; and   a rotating body including a rotating-body-side encircling member that encircles the shaft, and a hub which is fixed to the rotating-body-side encircling member and on which a recording disk is to be mounted,   wherein:   a first dynamic pressure generating groove is formed in either one of an inner periphery of the rotating-body-side encircling member and an outer periphery of the shaft, and a second dynamic pressure generating groove is formed in either one of the inner periphery of the rotating-body-side encircling member and the outer periphery of the shaft at a location which is distant from the first dynamic pressure generating groove in an axial direction and which is an opposite side to the base-side encircling member;   a first capillary seal portion and a second capillary seal portion are provided in a gap between the fixed body and the rotating body, and a path of a lubricant is present therebetween from the first capillary seal portion, the first dynamic pressure generating groove, the second dynamic pressure generating groove, and the second capillary seal portion in this order;   the base-side encircling member comprises a cylinder part encircling a part of the rotating-body-side encircling member; and   the first capillary seal portion is provided on an outer periphery of the cylinder part.   
     
     
         2 . The rotating device according to  claim 1 , wherein the first capillary seal portion is located between the first dynamic pressure generating groove and the second dynamic pressure generating groove in the axial direction. 
     
     
         3 . The rotating device according to  claim 1 , wherein:
 a part of the shaft at the base side is fixed to the base-side encircling member by interference fitting; and   the base-side encircling member is fitted in and bonded and fixed to the through-hole of the base.   
     
     
         4 . The rotating device according to  claim 1 , further comprising an external-side encircling member which encircles the cylinder part and which is fixed to the hub,
 wherein the first capillary seal portion is provided between an inner periphery of the external-side encircling member and the outer periphery of the cylinder part.   
     
     
         5 . The rotating device according to  claim 4 , wherein:
 the base includes a protrusion that protrudes from a surface of the base at the hub side so as to encircle the external-side encircling member; and   the protrusion and the external-side encircling member form a labyrinth seal.   
     
     
         6 . The rotating device according to  claim 5 , wherein a width of the labyrinth seal in a radial direction is equal to or smaller than ⅕ of a length of the labyrinth seal in the axial direction. 
     
     
         7 . The rotating device according to  claim 5 , wherein:
 a core including an annular part and a salient pole extending outwardly in the radial direction from the annular part is fixed to an outer periphery of the protrusion; and   a magnet facing the salient pole in the radial direction is fixed to the hub.   
     
     
         8 . The rotating device according to  claim 1 , wherein a third dynamic pressure generating groove is formed in either one of an end face of the cylinder part and a surface of the rotating body facing with the end face in the axial direction. 
     
     
         9 . The rotating device according to  claim 1 , wherein:
 the fixed body includes a hub-side encircling member which encircles a portion of the shaft at the hub side and which is fixed to the shaft; and   the second capillary seal portion is located between the hub-side encircling member and the rotating body.   
     
     
         10 . The rotating device according to  claim 9 , wherein a fourth dynamic pressure generating groove is formed in either one of a surface of the rotating-body-side encircling member and a surface of the hub-side encircling member, which surfaces face with each other in the axial direction. 
     
     
         11 . The rotating device according to  claim 9 , wherein a cap that covers the second capillary seal portion and a part of the hub-side encircling member is fixed to the rotating body. 
     
     
         12 . The rotating device according to  claim 1 , wherein:
 the shaft includes a shaft periphery that is a side face decreasing a diameter toward an opposite side to the base in the axial direction;   the rotating-body-side encircling member includes a second inner periphery that is a side face encircling the shaft periphery and decreasing a diameter toward the opposite side to the base in the axial direction; and   the second capillary seal portion is provided between the shaft periphery and the second inner periphery.   
     
     
         13 . The rotating device according to  claim 1 , wherein the rotating body includes a pathway that causes the first capillary seal portion and the second capillary seal portion to be linearly in communication with each other. 
     
     
         14 . A rotating device comprising:
 a fixed body including a base formed with a through-hole, a base-side encircling member fixed to the through-hole, and a shaft fixed to the base-side encircling member; and   a rotating body including a rotating-body-side encircling member that encircles the shaft, and a hub which is fixed to the rotating-body-side encircling member and on which a recording disk is to be mounted,   wherein:   a first dynamic pressure generating groove is formed in either one of an inner periphery of the rotating-body-side encircling member and an outer periphery of the shaft, and a second dynamic pressure generating groove is formed in either one of the inner periphery of the rotating-body-side encircling member and the outer periphery of the shaft at a location which is distant from the first dynamic pressure generating groove in an axial direction and which is an opposite side to the base-side encircling member;   a first capillary seal portion and a second capillary seal portion are provided in a gap between the fixed body and the rotating body, and a path of a lubricant is present therebetween from the first capillary seal portion, the first dynamic pressure generating groove, the second dynamic pressure generating groove, and the second capillary seal portion in this order;   the base-side encircling member comprises a cylinder part encircling a part of the rotating-body-side encircling member;   the fixed body includes a hub-side encircling member which encircles a portion of the shaft at the hub side and which is fixed to the shaft;   the first capillary seal portion is provided on an outer periphery of the cylinder part; and   the second capillary seal portion is located between the hub-side encircling member and the rotating body.   
     
     
         15 . The rotating device according to  claim 14 , wherein the first capillary seal portion is located between the first dynamic pressure generating groove and the second dynamic pressure generating groove in the axial direction. 
     
     
         16 . The rotating device according to  claim 14 , further comprising an external-side encircling member which encircles the cylinder part and which is fixed to the hub,
 wherein the first capillary seal portion is provided between an inner periphery of the external-side encircling member and the outer periphery of the cylinder part.   
     
     
         17 . The rotating device according to  claim 16 , wherein:
 the base includes a protrusion that protrudes from a surface of the base at the hub side so as to encircle the external-side encircling member; and   the protrusion and the external-side encircling member form a labyrinth seal.   
     
     
         18 . The rotating device according to  claim 17 , wherein a width of the labyrinth seal in a radial direction is equal to or smaller than ⅕ of a length of the labyrinth seal in the axial direction. 
     
     
         19 . The rotating device according to  claim 14 , wherein a third dynamic pressure generating groove is formed in either one of an end face of the cylinder part and a surface of the rotating body facing with the end face in the axial direction. 
     
     
         20 . The rotating device according to  claim 14 , wherein the rotating body includes a pathway that causes the first capillary seal portion and the second capillary seal portion to be linearly in communication with each other.